• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.487-488
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• 2008

The dry and wet flashover characteristics on the contaminated distribution facilities was investigated. The test were carried out on the suspension insulator, line post insulator, lightning arrester, cut off switch, etc. In the dry state, the flashover voltages of facilities contaminated with B, C, D classes are similar to the non-contaminated ones. However, in the wet state, the flashover voltages of facilities contaminated with B, C, D classes are decreased. The flashover voltages of some few facilities show under the standard value. This results indicate that the high humidity may cause the flashover on distribution facilities.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1166-1170
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• 2004

The leakage currents of transmission insulator were investigated as a function of environmental conditions, such as temperature, humidity, and rainfall. The insulators were artificially contaminated with insoluble yellow soil and kaolin which helped salt to stick on the surface of insulator. The insulators contaminated with the grade of B, C, and D were installed in the KoChang Testing Center. The leakage currents were measured and compared with non-contaminated insulators. The results indicated that the most important factor affecting leakage current was humidity. After heavy rain, the artificially contaminated salt was dissolved, resulting in similar characteristics between with and without contamination

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.203-206
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• 2001

Since th three sides of korea peninsula are surrounded by the sea, electric apparatus are greatly contaminated by the salt generated by the typhoon, seasonal wind, sea wind and sea fog. This contamination causes electric power apparatus to fail. Thus in this paper, we investigated to influence upon electrical properties of outdoor insulators with non-uniformity contamination in the experimental condition because The contamination of outdoor insulator highly depended wind property In the service condition, insulator was not uniformly contaminated. From the flashover test for the 254 mm suspension insulator, we could determine the influence non-uniform contamination on the electrical property of insulators. Through the experiment, we convinced to occur flashover from non-uniform contamination region of outdoor insulator. Contaminated area and pattern has a close relationship with the electrical properties of outdoor insulator.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.9
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• pp.464-469
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• 2004

The leakage current of transmission insulators contaminated with salt, clay, and kaolin was examined in the Gochang's Long Periods Testing Center. The Insulators were artificially contaminated and estimated with the method of equivalent salt deposit density(ESDD). The artificially contaminated insulators were installed with the same condition as in the real transmission power line and applied with 154 (kV). The leakage current of the artificially contaminated insulators was measured with environment conditions, such as temperature and humidity by the a automatic leakage current detecting system. The leakage current of heavily contaminated insulator was abruptly increased above 72［%］ of humidity, even though the leakage current was similar between the contaminated and non-contaminated insulators below 72［%］ of humidity. Also, it was found that the humidity was much more important than the temperature in the leakage current of transmission insulators. The leakage current of contaminated insulator was decreased when it was plenty of rainfall, resulting from natural washing.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.7
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• pp.364-369
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• 2004

In this Paper, a flashover prediction method using the leakage current in the contaminated EPDM distribution polymer insulator is proposed. The leakage currents on the insulator were measured simultaneously with the different salt fog application such as 25g, 50g, and 75g per liter of deionized water. Then, the measured leakage currents were enveloped and transformed as the CDFS using the Hilbert transform and the level crossing rate, respectively. The obtained CDFS having different gradients(angles) were used as a important factor for the flashover prediction of the contaminated polymer insulator. Thus, the average angle change with an identical salt fog concentration was within a range of 20 degrees, and the average angle change among the different salt fog concentrations was 5 degrees. However, it is hard to be distinguished each other because the gradient differences among the CDFS were very small. So, the new weighting value was defined and used to solve this problem. Through simulation, it Is verified that the proposed method has the capability of the flashover prediction.

• 전기의세계
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• v.29 no.10
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• pp.653-659
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• 1980

The paper describes a new technique for the shape design of a bell-type porcelain locke insulator in contaminated environment. Early studies on the contamination performance of insulators indicated the need for an improvable shape to provide adequate insulation strength at normal operating voltages. In this paper, under lightly and heavily contaminated site severity, the variation of voltage distribution to leakage path at insulator surfaces analyzed by the complex admittance matrix using finite element method. By this results, the improvement of shape of insulators could be approached to the available condition in contaminated environments. In applicating to compare a standard disc type with a fog disc type insulator, this design technique is valid.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.386-391
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• 2004

To find out the reason of accident by being stained of insulators, this paper researched and analyzed the result of electrical characteristic test and field test of EHV insulator through artificial contaminated method. The best way to evaluate contaminated level of insulator surface is getting a contamination data by regional groups continually. But it is needed a lot of time and manpower. To overcome those difficulties, this research introduced ESDD(equivalent salt deposit density) measurement method which is adapted to the international codes of IEC and compared the relation between experimental test results which contaminated insulators by going through stain procedure and electrical measurement results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.467-470
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• 2000

This paper present the result of the investigation, electric properties of outdoor insulators with the difference of contaminated condition. In general, the humidity and the amount of soluble salts such as NaCl, MgCl$_2$are the most dominant factor. A mini-fog chamber with transparent acryl and the standard contamination solution with kaoline was used. The kaoline was applied with sprayer to get the specific ESDD and NSDD value, then the specimen was dried and installed horizontally. And to measure the leakage current and the ambient condition, such as relative humidity and temperature, a DAS system was developed with LabView. From the result, we could know the influence of contaminated condition. Contaminated area and pattern has a close relationship with the electrical properties of outdoor insulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.759-761
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• 2010

In order to monitor operating performance of contaminated outdoor insulators, a wavelet-based flashover prediction method is proposed. In most cases, the low-frequency components, namely, fundamental, $3^{rd}$, and $5^{th}$ harmonic components have been mainly used for the sake of the spectral analysis of the leakage current. However, in this paper, the detail coefficients of wavelet transform representing high-frequency components are used as important information to predict a flashover in the contaminated insulator. Experimental results verify that the proposed method has a superior capability for flashover prediction.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1449-1451
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• 2002

A developed 800kV class composite hollow insulator for $SF_6$ Gas Insulated Switchgear (GIS) was tested as to insulation with their surfaces contaminated. The wet power frequency withstand voltage of the silicone rubber housing was about 135kV at an equivalent salt deposite density of $5kg/m^2$, to sufficiently satisfy the required performance. According to IEC 60507, the salt fog withstand voltage was measured at 565kV, and the highest measured leakage current was below 0.2mA. Therefore, it was clarified that the composite hollow insulator has sufficient insulation performance even when it is contaminated on the surface.